It was a problem the Saito family had never faced in all their years of farming: what do you do with radioactive spinach?

A few weeks after Japan’s Fukushima Daiichi nuclear plant plunged into crisis on March 11, the Saitos were told their carefully cultivated spinach had been contaminated by radiation. But nobody told them what to do with the suddenly unsellable crop, says Kazuko Saito, who tills rice and vegetable fields near the Fukushima prefectural capital together with her husband and son.

So the family could only pile the spinach in a corner of a field – along with broccoli also likely to have been contaminated with radioactive caesium – and watch it slowly rot.

“It’s still sitting there and any caesium will just go into the soil,” Ms Saito says. “The situation is laughable.”

But Fukushima farmers are not laughing. The disaster has been catastrophic for their Y250bn ($3.3bn) agriculture sector – Japan’s fourth biggest producer of rice and second largest of peaches.

While most Fukushima produce is thought to have radiation levels that are negligible or far below precautionary safety standards, public fears of contamination combined with a lack of confidence in government controls have sent sales plunging across the prefecture.

Such worries are also threatening farmers in other eastern prefectures where fallout has been found. This is jeopardising Japan’s drive to become a major supplier of high value agricultural produce to Asian neighbours including China.

Just how risky contaminated produce might be is a matter of dispute. Radiation can cause cancer, but at low levels of exposure its effects are difficult or impossible to detect in health statistics.

Some scientists say current radiation limits are far too conservative and are causing unnecessary social and economic disruption. But others fret about the possible vulnerability of young children and the unborn, especially as the cumulative exposure of people in highly contaminated areas will be difficult to monitor.

Public faith in the government’s ability to protect consumers has been shaken by a premature declaration by the Fukushima governor in October that the prefecture’s entire rice harvest was below the limit for caesium radioactivity of 500 becquerels per kilogramme. The claim was based on 1,174 samples harvested from around the prefecture that were tested by sophisticated Germanium detectors.

But fallout from the plant was distributed unevenly and has accumulated in some places to form small “hot spots” of higher radioactivity. Rice from a small number of districts has since been found to contain up to more than double the 500bq/kg limit, sending authorities scrambling to impose localised shipment bans.

The Saito family fields were among those affected, although a privately organised radiation test suggested their fields are free of hot spots. This time, at least, their rice had already been harvested and now sits in an agricultural association storehouse while officials decide what to do with it.

But consumer dismay at the rice debacle has also hit sales of Fukushima vegetables and fruit.

“After the rice problems, things just froze up,” says Mikiko Watanabe, who grows peaches and apples in a valley 10km south west of the prefectural capital.

Ms Watanabe and her husband have loyal customers outside Fukushima who have made a point of buying their apples since the autumn harvest. But such support – and sales to a supermarket with its own radiation testing equipment – are still not enough to make up for a dearth in other local orders.

“Our apple sales are down by about half [in 2011],” Ms Watanabe says, blaming in part what she sees as overly negative media coverage of Fukushima that has turned the prefecture’s name into a byword for disaster.

Farmers can claim compensation from Tokyo Electric Power, the Fukushima Daiichi plant’s operator, which has already paid out nearly Y90bn to agricultural organisations around Japan. But many complain that compensation comes slowly and does not cover all their losses, never mind the hurt of seeing their crops wasted or spurned.

Ms Saito says there is deep anger at Tepco and the government for failing to prevent the crisis and for leaving farmers to deal with their radiation problems largely alone.

“Everyone feels absolutely furious, it just bubbles inside,” she says. “We feel like we could explode.”

… these are not “dosimeters” but “glass badges” that passively collect radiation information. It won’t help these children or their parents to avoid high-radiation areas and spots, it won’t tell them how much radiation they will have been exposed unless they are sent in to a company to interpret the data.

Radiation exposure is increased by a factor of a trillion. Inhaling even the tiniest particle, that’s the danger.

Yo: So making comparisons with X-rays and CT scans has no meaning. Because you can breathe in radioactive material.

Hirose: That’s right. When it enters your body, there’s no telling where it will go. The biggest danger is women, especially pregnant women, and little children. Now they’re talking about iodine and cesium, but that’s only part of it, they’re not using the proper detection instruments. What they call monitoring means only measuring the amount of radiation in the air. Their instruments don’t eat. What they measure has no connection with the amount of radioactive material.

Dr. Helen Caldicott (Co-founder of Physicians for Social Responsibility):

You’ve bought the propaganda from the nuclear industry. They say it’s low-level radiation. That’s absolute rubbish. If you inhale a millionth of a gram of plutonium, the surrounding cells receive a very, very high dose. Most die within that area, because it’s an alpha emitter. The cells on the periphery remain viable. They mutate, and the regulatory genes are damaged. Years later, that person develops cancer. Now, that’s true for radioactive iodine, that goes to the thyroid; cesium-137, that goes to the brain and muscles; strontium-90 goes to bone, causing bone cancer and leukemia. It’s imperative … that you understand internal emitters and radiation, and it’s not low level to the cells that are exposed. Radiobiology is imperative to understand these days.”